Research Oil Abstracts

Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production Effects of a dietary intake of the polyunsaturated omega-6 essential fatty acids (EFAs) linoleic and gamma-linolenic acids (GLA) on blood lipids, platelet function, and vascular prostacyclin production were studied 12 hyperlipidemic patients (doses of 3 g/day) and 12 male Wistar rats (doses of 3 mg/kg/day) for 4 months. In humans, GLA supplementation decreased plasma triglyceride (TG) levels by 48% (p < 0.001) and increased HDL-cholesterol concentration by 22% (p < 0.01). Total cholesterol and LDL-cholesterol levels were significantly decreased by omega-6 EFAs. Platelet aggregation induced by low concentrations of adenosine diphosphate (ADP) and epinephrine, and serum thromboxane B2 decreased by 45% both in humans and animals after GLA supplementation. Bleeding time increased 40% (p , 0.01). In rats, vascular prostacyclin production measured by radioimmunoassay of 6-keto-PGF1 alpha was enhanced by GLA intake. These effects of omega- 6 EFAs may contribute to cardiovascular protection and prevention of the atherosclerotic disease. Guivernau M, Meza N, Barja P, Roman O. Leukot Essent Fatty Acids 1994 Nov;51(5):311-316. Dietary fatty acid supplementation alters stress reactivity and performance in man Certain dietary polyunsaturated fatty acids, gamma linolenic (18:3n-6) and eicosapentaenoic (20:5n-3) acid, attenuate cardiovascular reactivity to stress in rats. To study their effects on cardiovascular reactivity to acute stress in man, 30 men were randomly assigned to one of three groups and given 28 day supplements of borage oil (containing 18:3n-6), fish oil (containing 20:5n-3), or olive oil (placebo). Reactivity to the Stroop colour-word conflict test was assessed prior to and following treatment. Borage oil alone attenuated blood pressure and heart rate responses to stress, increased skin temperature, and improved task performance. These data suggest that diet may be used to alter stress reactivity in man. Mills DE, Prkachin KM, Harvey KA, Ward RP. J Hum Hypertens 1989 Apr;3(2):111-116. Treatment of rheumatoid with gammalinolenic acid OBJECTIVE: To assess the clinical efficacy and side effects of gammalinolenic acid, a plant-seed-derivedessential fatty acid that suppresses and joint tissue injury in animal models. DESIGN: Arandomized, double-blind, placebo- controlled, 24-week trial. SETTING: Rheumatology clinic of a university hospital. PATIENTS: Thirty-seven patients with and active synovitis. INTERVENTION: Treatment with 1.4 g/d gammalinolenic acid in borage seed oil or cotton seed oil (placebo). MEASUREMENTS: Physicians' and patients' global assessment of disease activity; joint tenderness, joint swelling, morning stiffness, grip strength, and ability to do daily activities. RESULTS: Treatment with gammalinolenic acid resulted in clinically important reduction in the signs and symptoms of disease activity in patients with rheumatoid arthritis (P < 0.05). In contrast, patients given a placebo showed no change or showed worsening of disease. Gammalinolenic acid reduced the number of tender joints by 36%, the tender joint score by 45%, swollen joint count by 28%, and the swollen joint score by 41%, whereas the placebo group did not show significant improvement in any measure. Overall clinical responses (significant change in four measures) were also better in the treatment group (P < 0.05). No patients withdrew from gammalinolenic acid treatment because of adverse reactions. CONCLUSION: Gammalinolenic acid in doses used in this study is a well-tolerated and effective treatment for active rheumatoid arthritis. Gammalinolenic acid is available worldwide as a component of evening primrose and borage seed oils. It is usually taken in far lower doses than used in this trial. It is not approved in the United States for the treatment of any condition and should not be viewed as therapy for any disease. Further controlled studies of its use in rheumatoid arthritis are warranted. Leventhal LJ, Boyce EG, Zurier RB. Ann Intern Med 1993 Nov 1;119(9):867-873. Gammalinolenic acid-enriched diet alters cutaneous eicosanoids There are reports that vegetable oils containing gammalinolenic acid (GLA) may exert beneficial effects on inflammatory skin disorders. To determine whether or not dietary GLA exerts any modulatory role on cutaneous eicosanoids, guinea pigs were fed either a control diet containing safflower oil (less than 0.5% GLA) or borage oil, a GLA-rich diet containing 25% GLA. After an 8-week feeding period, epidermal samples from both animal groups were analyzed for fatty acid composition and tissue eicosanoids. Analysis of epidermal neutral lipids and phospholipids in borage oil-fed animals showed a marked increase in GLA and its elongase product, dihomogammalinolenic acid (DGLA). Similarly, analysis of epidermal eicosanoids in the borage oil-fed animals revealed significant increases in the amounts of the 15-hydroxy fatty acid (15-OH-20:3n-6) and PGE1, both metabolites of DGLA. Since these metabolites have anti-inflammatory potential, our results suggest that increased dietary GLA could result in the generation of local anti-inflammatory metabolites thus providing a non-toxic approach to suppression of cutaneous inflammatory skin disorders. Miller CC, Ziboh VA. Biochem Biophys Res Commun 1988 Aug 15;154(3):967-74.

The preceding abstracts were obtained from the Medline service maintained by the National Institutes of Health.